Generally speaking, radar warning receivers are basically instantaneous frequency measurement receivers or radio frequency (RF) receivers that are typically used in electronic warfare. Utilizing interferometric techniques by detecting the phase shift magnitudes produced in multiple calibrated delay lines, radar warning receivers can measure the frequencies of signals radiated from hostile radars and the frequencies of incoming RF signals.
With the advent of multi-gigahertz speed logic, a mono-bit sampling technique followed by a broadband channelized digital receiver has become an effective way to achieve gigahertz bandwidth with adequate sensitivity. The primary drawback is that strong signals with a very high signal-to-noise ratio can cause problems. In particular, high-powered signals above a broadband noise causes several issues with the measured results at specific clock to signal ratios and also there is no way to recover good amplitude information from the strong signals. In addition, other signals similar in amplitude are suppressed and distorted, and the distortion can cause measurement errors on the strong signals.
One solution to the above-mentioned problems is to use log detection amplifiers to measure amplitudes of strong signals, and the sampling frequency can be changed when a signal appears to be at a bad clock-to-signal frequency ratio. This approach requires a significant amount of extra active components, and importantly, does not respond fast enough to obtain reliable measurements on every signal.
Consequently, it would be desirable to provide an improved radar warning system with better dynamic range and more consistent accuracy while still maintaining a simple and low-cost design.